Body mounted bulldozer



June 24, 1958 H. H. wAsHBoND BODY MUNTED BULLDozER 5 Sheets-Sheet 1 Filed May 9. 1951 June 24, 1,958 H. H. wAsHBoND 2,839,850k

BODY M ouNTED BULLnozER 5 Sheets-Sheet 2 Filed May 9, 1951 mil A fnl/5172271 HaQyHVaS/zo/zd i u s l 5225/5 tjjqjjjjfj M zy mwN.

June 24, 1958 H. H. wAsHBoND BODY MOUNTED BULLDOZER 5 Sheets-Sheet 3 Filed May 9. 1951 June 24, 1958 H. H. wAsHBoND Booy MOUNTED BULLDozER 5 Sheets-Sheet 4 Filed May 9, 1951 H. H. WASHBOND BODY MOUNTED BULLDOZER June 24, 1958 Filed May 9, 1951 5 Sheets-Shedl 5 Hm@ ff Was/Mazza? vasignments, to.y Allis-Chalmers `Manufacturing Com- `lltllly, a corporation of Delaware f Applnaon May 9, 1951, serial No. '225,363

i 12 claims. (c1. 31-144) This invention relates to implement equipped vehicles, such as bulldozers, angle dozers, snow plows, and the like, which are placed at the desired operating level by swinging the vehicle Abody relative to the, vehicle supports.

A MoreV specifically this invention relates. to a bodymounted bulldozer havingthe dozer bladeatlixed to the front end of a tractor and raised and lowered with-the front end of the tractor body by fluid pressure actuated jacks acting between the tractor and the tractor track frames. Y,

The invention will be hereinafter specifically described as embodied in a bulldozer, but it should be understood that the principles of this invention are generally applicable to' other types of earth or snow moving equipmentl mounted on vehicles such as tractors or the like.

Heretofore, bulldozer blades have been carried on push beams which are pivotally mounted onV a tractor. The pushY beam mounted blade was swung relative to the tractor by means of actuators such as cables, iluid pressure actuated jacks, or other linkages. In all of these heretofore known push beam mounted bulldozer blade arrangements, the blade had to be'positioned sufficiently forward from the vfront end of the tractor so that it could be swung through -itsY operating arc without striking or rubbing against the tractor. The resulting forward spacing of the implement blade interfered with the fore and aft operating balance of the tractor, and placed heavy strains on the tractor parts. Further, when the blade was operated at high levels, the view of the operator was substantially obstructed. 4Similar clearances had to be provided vbetween the swinging push beams and the tractor, thereby increasing the over-all width as well as the over-all length of the assembly. The dozer blade had to be made sufficiently wide to extend at least up to the front ends of the pushrbeams and it'was not possible to design the blades ofdesired height without creating a pushing frontal area in excess of the available pushing force of the tractor.

` .Hind States Patent The present inventionnow eliminates alljof the afore-v i said objections and provides a bulldozer .assembly free from p ush beams. 'According to this invention; the dozer blade is iixedly mounted on the front end ofthe tractor body. In a conventional tractor, the bodypivots around rear axles supported by track frames carrying'the crawler tracks therearonnd. A transverse spring having its ,ends carried on the track frames underlies the tractorbody to support the front end thereof.- In accordance with this invention, the tractor spring is removed and the Vfront end of, the' tractor body is adjustably supported on the track frames by iluid pressure actuated jacks. These track'frames. The lever varrangement eliminates loadsonk :2,839,850 Patented June 24, 1958 The assembly is free from any extensions with increase the width of the tractor and, since the blade is adapted to be mounted ilush against the front end of the tractor, the fore and aft balance of the tractor is not disturbed. An important yfeature of the' invention resides in direct utilization of the full weight of the front end of a tractor body for digging pressure on a dozer blade.

' Another feature of the invention resides vin the utilization of substantially the full combined weights of the 'front ends of the tractor body and track assemblies for digging pressure `on the dozer blade. n

Another feature of the invention resides in the provision of a bulldozer which has a blade swingable through a wide arc without ever obstructing the view of the operator.

' An object of the invention is to provide earth or snow moving equipment which operates as an integral part of a vehicle body.

Another object of the invention is to provide a bulldozer or the'like tractor machine having an implement carrying body swingable about its supporting frame in response to operation of fluid pressure controlled jacks bottomed onv the supporting frame. Y

A furtherobject of the invention is to provide a tractor HYwith hydraulic jacks operatively connected between the tractor body and the tractor track frames to swing the front end of the tractor body without placing a torsion load on the track frames. l

A still further object of the invention is to provide a bulldozer free from push beams and other linkages which increase the over-all width of the machine.

A still further object of the invention is to provide a bulldozer having a blade frame affixed to the front end of a tractor body and pivotally supporting hydraulic jacks at the sides of the body which act on the front ends 'of the tractor track frames through shiftable links accommodating a substantially direct lift of thebody irrespective of the degree of inclination of the body relative to the track frames.

A further object of the invention is to provide a narrow width bulldozer machine which will push as much earth V.as a wider Amachine by virtue of the increased height of the dozer blade and which will have an enhanced digging capacity because of its reduced width.

A still further object of the invention is to provide a bulldozer which has a blade mounted directly on the front end of the tractor body close to the tractor tracks, thereby providing a quick digging'approach. l

Other and further objects of the invention will be apparent to those skilled in the art from the following detailed description ofy the annexed sheets of drawings 'which, byk way of preferred' examples only, illustrate several embodiments of the invention.

On the drawings:

Figure 1 is a side elevational View of one form of bulldozer machine according to the invention and illustrating in dotted lines a raised position of the machine.l

Figure 2 is a plan View of the machine of Figure l. Figure 3 is a'phantom view illustrating the fully raised land lowered positions of the machine to better show the ,g substantial-ly direct lift application of the hydraulic jack.

the track frames which would tend to` tipl them inwardly I not'need'to extend in front of any push beam' mounting. Y

Figure 4 is a diagrammatic view illustrating the manner in which the hydraulic jacks are in intercommunication. v Y

Figure Sis a side elevationalview similar to Figure l --but illustrating a modied arrangement wherein the yweight of the track assemblies can be added to the digging force of the dozer blade.

Figure 6 is a fragmentary plan view of the linkage between 'the tractorbody and track frames in the machine ofJFigu're 5.

Figure 7 is a vertical cross-sectional view, with parts in elevation, taken'along the line 77 of Figure 6.

Figure 8 is a diagrammatic View similar to Figure 4 illustrating the manner in which the hydraulic jacks of the embodiment of Figure are placed in intercommunication.

As shown on the drawings:

The bulldozer machine 1i) of, Figures 1 toY 3 includes a crawler type tractor 1.1 having a main Ibody 12 and crawler track assemblies 13, 13 on each side of the main body. The body 12 includes an engine radiator 14 at the front end thereof, a hood 15 under which is mounted an internal combustion engine (not shown). A drivers seat 16 is provided at the rear end ofthe body. Axles TJ?, 17 project laterally thru gear casings at the rear end of the body and are xedly supported by the body. Brackets 13 are sw-ingably mounted on the inner ends of the axles 17 and brackets 19 are swingably mounted on the outer ends of these axles. Driving gears 20 driven by the engine are also rotatably mounted on the axles between the `brackets 18 and 19.

The crawler track assernblies 13 each include an inn ner track frame 211 having its rear end carried by lbracket 18 and an outer track frame 22 having its rear end carried by the bracket 19. The inner and outer frames arc in spaced parallel horizontal relation and afford supports for bottoni load carrying idler rollers 23 (Figure l), a track tightening assembly 24, and a front pulley roll 25 acted on by the assembly 24. An endless belt 26 of crawler tracks is trained around the gear 2t) and roll 25 and under the rollers 23 along its lower run. An idler guide roll 27' is also carried by the inner track frame 21 to support the upper run of the crawler tracks as it passes `between the gear 20 and front roller 2S.

The track assemblies 13 are independently swingable about the axles 17 relative to the tractor body 12 and the track frames 21 and 22 of each assembly are integr-ally connected as a unit.

in conventional tractors, a transverse spring is mountedunder the tractor body 12 and is supported 'at its ends on the inner track frames 2l near the front roller 25. In accordance with this invention, however, the conventional tractor spring is dispensed with and in its place there is provided a bracket 28 on cach inner track frame 21 in the same position usually occupied 4by the bracket for the end of the tractor spring. Each bracket 28 has an upstanding ear straddled by metal links 29 which are pivoted to the ear by means of a pin 30. The upper ends of the links 29( terminate in spaced relation 'beneath the upper run of the crawler tracks 26 and the links have sufficient clearance between the assembly 24 and the adjoining bearing support for the front roller 25 that they can swing about the pin 3i) through an appreciable arc without striking any adjacent tractor structure.`

A bulldozer `blade and frame unit or attachment 31 is mounted on the front end of the tractor body 12 and includes a blade 32 extending transversely across the front end of the tractor and terminating substantially hush with the outer ends of the track assemblies 13. The `blade 32 is backed by suitable reinforcing framework 33. lA pair of arms or brackets 34 integrally affixed to the framework 33 extend rearwardly from the blade to straddle both sides of the tractor body 12. Each bracket 34% extends to a position adjacent the bracket 28. Each bracket 34 has an outturned top flange 34a around its upper edge and extending across its rear face. An angle lbracket 35 secured, as by the welding or the like, on the main side beam 12a of the tractor body 12 has an ouh turned ,leg Vbacking up the rear lface of the flange 34u and bolted thereto by means of bolts 36.

Additional bolts 37 (Figure 2) also connect the yflat vertical face of the bracket 34 to the main body frame beam 12a.

Each bracket 34 has a vertical extension alongside Vof the tractor engine hood 15 and the upper end of 4thisex--k tension has an integral Vdepending ear 34b on which is pivotally suspended a hydraulic jack 38. A pivot pin 39 connects the top end of tlgfe cylinder or upper portion 38a of the jack 38 to the ear 34b and the piston 3811 of the jack depends from the 'bottom end of the cylinder 38a. The jack 38 is free to swing through a llirnited arc lbetween opposite flanges 34a of the bracket 34.

Ears or lugs 40 on the frame 33 carry a pin 41 extending laterally outward from each bracket. 34 at the front end thereof. 7 I

A lever 42 is provided along the outer face'of leach bracket 34 and has a front end boss pivotally mounted on the pin 41. The lever 42 extends rearwardly in spaced parallel relation with the face of the bracket 34 under the hydraulic jack 38 and then turns outwardly along an inclined leg portion 42a thereof to a rearwardly extending flattened ear portion 42b disposed above the inner track frame 21 and tting between the Alinks 22. Apivot pin 43 connects the links'with the ear 42,11. 'Ihe leyer 42 is thereby pivotally supported lat its Ifront end on the f rarne 33 and at its rear end on the links ,23 Whih anpivot about the pin 30 carried by the bracket 2 8, y j j An ear 44 is provided on top of the lever 42 ahead of the olset portion 42a thereof and is pivotally cpnnected.V by a pin 45 to an ear 38a on the lower end of 4the piston or lower portion 38h of jack 38. The `l 1yclra1 r l ic .ja'ckm328-v thereby has the upper end of its cylinder pivoted to th, upper end of the bracket 34 and the lower end of ts piston pivoted to a rear end portion of the lever g2g.,

The blade assembly 31 has the blade 32 thereof hrungdiately in front' of the engine radiator Maud Si etbg;V assembly is integrally affixed to the tractor body no` provision for relative movement therebetween, unclearance need be provided between the radiator andA blade, and the blade is therefore carried closet to the fro of the crawler tracks 26 than has heretofore been p qsgble.` The assembly 31, in effect, straddles the front endpf they, tractor body and serves to reinforce yand brace t tdy.`

The upper ends ofthe jack cylinders 38a have n i6 for owing hydraulic fluid through lthe cylinders, A the pistons 38a. Each nipple 46 is connected with ya ge-. ible hose 47`- Each hose 47,` in turn, is connectedltppa-p T fitting 48 having the third fleg thereof coupled to. ,a5 hose or tube 49. As brest shown in Figure 4, a value 5.9, controls ow of hydraulic fluid from 4a' purnp 5 1 fed' b'y a tank y52 which iscarried on the tractor body; return conduit 5,3 is provided between the valye andvltaiik for return of hydraulic fluid `such as oil yback to the ta Hydraulic fluid can always llow freely Abetv veeu ,th 1 cylinders 38u through the T coupling 48 places the, cylinders in fluid intercommunication. Fluid is latlsulgrxsiup-A plied under equal pressure to the top of each piston As the pistons 38h Aare extended, being forced doyvn` wardly out of thelower ends of the cylinders 38a under the influence of hydraulic pressure, an elongation is provided in the only linkage connecting the front end vof the tractor body with the front ends of the track assemblies, aud the vbodyV 12 is swung about its axle pivots to raise the Yblade assembly 31 therewith as best illustrated in Figa u res 1 and 3. Conversely, the jacks 38 are .contracted when the valve 5t) `is set so as to allow return fof the ,hy,k draulic uid to the tank S2, ,the weight of the Vbody `forfe-y ing the pistons38b back into Vthe cylinders 38a, thereby shortening the linkage between ythe track assembliesand the body and allowing the body :to swing downwardly.

During the pivoting `of the body l,about its, axles 17. relative to the track assemblies, they links y29v will swing as illustrated in Figures l and 3 .to Vaccornrnodate lthe shifting position of the rear `end of `the lever ,42 due .to y the ,changing position ko f the lever pivot .41 relative ,tothe link pivotjlail. It willV .be .noted that the hydraulic jack remains in a substantially upright position throughput the full- .extent ,of the Swinging movement ,of the tractor hoods' to apply an effective lift to the body without straining the, pivot connections. Since the jack is connected to `the l lever `42`closely adjacentthe points of connectionl of the lever with the track frame,a substantially direct lift eiect is obtained. l i g The lever 42 serves a very important function in relieving the track frame 21 from torsion loads tending to tip the frame inwardly under the load inuence of Lthe tractor, body and blade assembly.` This torsion load is transmitted by the lever` 42 into the pivot pin connection 41 where it is resisted, so that the load is yapplied to the track frame in a straight vertical direction. The assembly therefore makes possible positioning of the lifting jacks 'Y 33m an out 'of the way position between the ,tractor body and the track assemblieswithout creating a torsion load onl the trackV assemblies.-

As best shown in Figure 3, the blade assembly 31 has a wide range of operating positions from a low level position which is well below the lower run of the crawler tracks to a high position which issubstantially above ground level. The invention makes -it' relatively 'simple 'minates at a level below the top of the engine hood 15,

the operator on seat ,16 always has a full unobstructedview of the blade operation, even in the high level posi-- tion of the blade.y Y Y The hydraulic jack connection between the tractor track frames and the tractor body coupled with the non-movable fixed connection between the blade assembly and the front end of the tractor body provides for maximum'digging pressure on the bulldozer blade, because the full dead weight of the frontend of the tractor body including the heavy engine carried at the front end is directly applied to theblade. This has heretofore not been possible `in prior known bulldozer machines. v

Asbest shown in Figure 2, the bulldozerblade 32 Vdoes not project laterally beyond the outer faces of the'track assemblies 13 and anarrow width bulldozer machine is thereby provided with no obstruction at the sides. At the same time, however, the blade 32 can have the full earth moving capaci'tyof a wider blade, because it can be increased in height without projecting above the `radiator. Ample .frontal area of the radiator is thereby always exposed for eicient cooling of the engine. l r

The bulldozer machine 10a of Figures 5 to 8 operates on thev same principle as the above described machine 10, but provides for the addition of the weightvof the track Y assemblies 13 to increase the digging pressure of the blade assembly 31. In Figures 5 to 8, parts identical with parts described in Figures l to 4 have been marked with the same reference numerals.

VAs best shown in Figures 5 and 6 the blade assembly or attachment 3i has rearwardly extending relatively llat` Y end of the lever 62.

A bracket 67 on the trackframe 21' at the same location where the Vends of the conventional tractorspring would normally be mounted has a pair of opstanding ears receiving the lower end of the link therebetween. A pivot pin 68 pivotally connects the link with the bracket 67. The lever 62 therefore is pivotally supported 'at its front end on'the blade assembly 31 in the sarnemanner as described in connection with the bulldozer machine 10, but the offset end of the lever 62b is connected ahead of its rear end through a swivel connection with va link` that can shift in response to variationsv` in .the distance between the pivot pin 41 and the bracket 67 as the tractor body pivots about its rear axle. As in the bulldozer machine 10, the lever 62 serves as does lever 42` (Fig. 5) to ltransmit torsion loads to be resisted by the pin 4i which would otherwise tend to tip the track frame 21 inwardly.

The rear end of the otset lever portion 62b is provided with a boss 62d on its inner face in spaced rearward relation from the boss 62C. This boss 62d has a laterally projecting stud 69 carrying a spherical bearing 71B which is held thereon by means of a nut 71 threaded on the stud .Y

The main frame 12a of the tractor body 12 has a reinforcing apertured spacer plate 72 aixed to the outer face thereof behind the plate 60. A cylinder mounting bracket 73 having a stud 74 projecting into the aperture I of the plate 72, is bolted to Vthe plate by means ofbolts 75. The bracket 73 has spaced parallel outturned anges 73a with bearing bosses at the upper ends thereof pivotally supporting studs 76 of a ring 77 disposed between the flanges. The ring 77 surrounds the cylinder '78a or upper portion of a hydraulic jack 78 and the cylinder v is pivotally mounted in the ring on studs 79. A universal joint connection is thereby provided between the cylinder 73a Iand the bracket 73.

The hydraulic jack 78 hasy a piston 78b slidably mounted therein with a piston rod 78a` or lower portion projecting kthrough the lower end of the cylinder 78a and carrying a lug 78d at its lower end swivelly receiving the sphere so as tto connect the piston rod withthe rear Each hydraulic jack 78 has a nipple B0 communicating with the upper end of the cylinder 78a thereof. A similar nipple 81 communicates with the lower end of the cylinder. Each nipple El@ receives a flexible hose 82 as best shown in` Figure 8 which is connected to a T fitting 83. Flexible hoses 84 connect the nipples 8l with a T fittingl S5. Hoses o-r pipes 86 and 87. respectively conneet the Tfttings 33 and 85 with a Valve 88. A pump 89 supplies hydraulic uid from a tank 9) to the valve S8. A fluid connection 91 between-the valve and the tank 90, provides for return llow of the hydraulic fluid. The upper ends of the cylinders 78 are thereby in free fluid intercommunication through the fitting 83. The

lower ends of the cylinders are likewise in iluid intercom' munication through the fitting 85,.V The hydraulic jack 78 is double acting and is further denable as being eX- tensible and contractible. The valve S8 can be manipulated to positively force the pistons 78b either upwardly thereby extending the jack 78 or downwardly thereby contracting the jack 78 in the cylinder 78a but in either r instance `the same pressures will be applied to each piston A cylindrical rod or tube 62 has the front endthereof t pivotally supported on the pin 41 carriedv by the lugs or lears tti'of the blade assembly 31 and projects rearwardly therefrom in parallel relation with the side beam or bracket plate 6u to an outturned portion 62a terminating in a parallel offset end 62b which is just inwardly from the inner track frame 21.

As best shown'inl Figure 7, this offset end 62b has a boss 62e on its v-outer face carrying a laterally extending `stud 63 which projects Aover the track frame 21. A

spherical bearing V64 iscarried on the stud and swivelly supports link 65; 4A nut 66threadedon the stud 63 holds the bearing and linkin position.

78b due to the intercommunication between the cylinders 78a. YSince thepistonrods 78a are swivelly connected with the rear ends of the levers 62, which levers, in turn, are connected through the links 65 with the track frames 21, a raising and lowering of the pistons 78b by the hydraulic lluid will shorten or elongate the only connections between the frontr ends of the track frames and theffront end of the tractor body, so that the tractor body will be caused lto swing about its pivot axles 17 as shown in Figure 5. However, since the pistons 78b can also receiveiluid on their lower facesrand thereby force the pistons 78h upwardly in the cylinders, it is possible' to add the weight of the front ends of the track assemassassinv Sfr lustrated in Figure 5. As therein pressure on the hydraulic jacks will serve to raise the frontends of the crawler tracks from their dotted lin*l position, thereby adding the weight of these front ends to the digging point of the blade 3.2. Whenthe llnid pressure is applied to the top ends of the pistons in the jacks '78,'the piston rods 73e will be moved outwardly from the cylinders and the tractor body will be iai-:ed to the dotted line position. in this position, the di ,D pressure in the blade is not influenced by the weight of the track assemblies, since the tracks will be in full lcontact with the ground along their bottom ran, shown in dotted lines.

The swivel connections between the i the levers, and between the levers and the lin allow -fo'r misalignment without stressing the connected parts. These swivel connections function as torque ob- Sorbing joints in that they provide .added insu against transmission of torsion loads to the track .trarne since twisting movements of the lever cannot be transmitted through these joints.

From the above descriptions it will therefore be onderstood that this invention provides body mounted bulldozer wherein a bulldozer blade assembly is fixedly mounted on the front end of a, tractor body to move as a unit therewith and wherein either single acting. cr double acting upright hydraulic jacks form the only connections between the front end of the tractor body and the front ends of the tractor track assemblies for swinging the body about the pivots between the track blies and the body. The jacks act with straight line forces in substantially vertical planes between the tractor body and track frames. Linkages between the tractor body and track frames prevent transmission of torsion loads to the track frames, so that specially designed tractor parts or reinforcements are not necessary.

It will be understood that modications and variations may lbefeplected without departing from the scope of the novel concepts ofthe present invention.

I claim as my invention:

l. A bulldozer comprising a tractor having a body, a crawler track assembly on each side of the body, pivot means connecting the rear end portions of the body and track assemblies, each track assembly having a pair of horizontally 'aligned spaced parallel longitudinal track frames, a blade assembly secured to the front end of the body and extending laterally in front of the track assemblies, a'lever between each side of the bodyand the adjacent crawler track assembly, torque resisting horizontal pivots kon the rear face of the blade assembly mounting said leviers for swindging movement in a vertical plane only, an offset portion on the rear end of cach lever extending over the adjacent inner track frame, a swingable link pivoted on the top face ,of each inner track frame and extending upwardly thereof, a swivel torque absorbing joint connecting the upper end of each link with the offset end of the'adjacent lever, and an upright hydraulic jack pivotally interposed between the lever and vbody for direct lift action on the body to swing the blade and body about the pivot means without subjecting the inner track frames to torsion loads tending to tip the frames inwardly.

-2. In a bulldozer the combination of a tractor having a body; a crawler track assembly on Veach side of said body; pivot meansfconnecting the rear end portions of said body and track assemblies, said track assemblies being in parallel relationship to one another and each assen'- having a track frame; an earth-working tool Vassembly secured to the front endv .of the bodyl andV extending laterally in .front of said track assemblies; and a pair of raising and lowering mechanisms operatively interposed between said body and said track assemblies, re-

spectively, each of said mechanisms comprising: a torsion lever having one end connected to said body for vertical vswingingimovement about a horizontal axis and having an elongated torque transmitting portion extending longitudinally of said tractor from said one end in transverse relation to said horizontal axis; connecting means for attaching said torque transmitting portion in vertical load' transmitting relation to the track frame of the adjacent trackv assembly; an upright jack having a pair of relatively extensible and Vcontractible elements, said jacks being disposed, respectively, between said body and said track assemblies;` attaching means connecting one ofk said elements to-said one side ofsaid body; and attaching means .pivotally connecting the other of said elements to said lever at a point spaced from said connecting means in the `direction of said horizontal axis.

3. ln a bulldozer the combination of a tractor having a body; a crawler track assembly on each side of said bodygpivot means connecting the rear end portions of said body andtrack assemblies, said track assemblies being in parallel relationship to one another each having a track frame; an earth-working tool assembly secured to the front end of the-body; and a pair of raising and lowering mechanisms operatively interposed between said body and said track assemblies, respectively,

Veach of said mechanisms comprising: a torsion lever having one end connected to said body for vertical swinging movement about a horizontal axis disposed in transverse relation to said tractor, said lever having an elongated torque transmitting portion intermediate its opposite ends disposed between said body and the adjacent tr'ack assembly; connecting means for attaching said lever in vertical load transmitting relation to the track frame vof the adjacent track assembly; an upright jack disposed between said body and the adjacent track assembly and having a pair of relatively extensible and contractible elements; attaching means pivotally connecting one of said elements to said one side of said body; and attaching means pivotally connecting the' other of said elements to said lever at a point spaced from said connectingmens in the direction toward said body, the line of thrust transmitted by saidv jack to said lever lying substantiallyin a vertical plane parallel to said track assemblies.

4. The bulldozer set forth in claim 3 wherein the connecting means for attaching said lever to the track frame includes a universal pivot connection.

5. The bulldozer set forth in claim 4Vwherein the attaching means forpivotally connecting the other of said elements to said lotherend of said lever includes a universal pivot connection. l

6. `In a bulldozer the combination of a tractor having a body; a crawler track l.assembly on each side of said body; 'pivot` means connecting the rearend portions of said body and track assemblies, said track assembliesv being in parallel relationship to' one another and each having a track frame; an earth-working tool assembly secured to the front end of the body; and a pair of raising and lowering .mechanisms operatively interposed between said body and said track assemblies, respectively, each of said mechanisms comprising: a torsion lever having one end connected to said body for vertical swinging movement about a horizontal axis and having an elongated torque transmitting portion intermediate its opposite ends extending longitudinally of said tractor in transverse relation to said horizontal axis, said lever having anl offset part at its other end extending in overlying relation -to said track frame of the adjacent track assembly; connecting means for attaching said oset part in vertical load transmitting relation to said track frame or the adjacent track assembly; an upright hydraulic jack disposed between saidone side of said body and the adjacent track assembly and having a piston element and a cylinder element; attaching means pivotally connecting one of ksaid elements to said one side of said body; and attaching means pivotally connecting the other of said elements to said other end of said lever at a point spaced from said connecting means in the direction toward said body.

7. ln a bulldozer the combination of a tractor having a body; a crawler track assembly on each side of said body; pivot means connecting the rear end portions of said body and track assemblies, said track assemblies being in parallel relationship to one another and each having a track frame; a blade assembly secured to the front end of the body and extending laterally in front of said track assemblies; and a pair of raising and lowering mechanisms operatively interposed between said body and said track assemblies, respectively, each of said mechanisms comprising: a torsion lever having one end connected to said body for vertical swinging movement about a horizontal axis and having an elongated torque transmitting portion intermediate its opposite ends extending longitudinally of said tractor in transverse relation to said horizontal axis, said lever having an offset part at its other end extending in overlapping relation to said track frame of the adjacent track assembly; a vertically disposed link having one of its opposite ends pivotally connected to said offset part and having the other of its ends pivotally connected to said track frame of the adjacent track assembly; an upright hydraulic jack disposed between said one side of said body and the adjacent track assembly and having a piston element and a cylinder element; attaching means pivotally connecting one of said elements to said one side of said body; and attaching means pivotally connecting the other of said elements to said other end of said lever at a point spaced in the direction toward said body from the connection between said link and track frame.

8. In a crawler tractor of the type having endless track running gear at each of its lateral sides, the combination comprising: a main body assembly; a track frame assembly for an endless track disposed at one side of said main body assembly; a iirst means pivotally connecting said track frame assembly to one side of said main body assembly for swinging movement about a rearwardly disposed transverse axis; an attachment rigidly secured to the forward end of said main body assembly including an earthworking tool disposed forwardly of said running gear; a horizontally disposed lever; a vertically disposed link having one end pivotally connected to said lever and having its other end pivotally connected to one of said assemblies; a second means pivotally connecting said lever to the other of said assemblies at a point spaced horizontally from the connection between said link and said one of said assemblies; and a vertically disposed extensible and contractible jack having its upper portion pivotally connected to said main body and its lower portion pivotally connected to said lever.

9. In a crawler tractor of the type having endless track running gear at each of its lateral sides, the combination comprising: a main body assembly; a track frame assembly for an endless track disposed at one side of said main body assembly; means pivotally connecting said track frame assembly to one side of said main body assembly for swinging movement about arearwardly disposed transverse axis; an attachment rigidly secured to the forward end of said main body assembly including an earthworking tool disposed forwardly of said track frame assembly; a horizontally disposed lever; a vertically disposed link having one end pivotally connected to said lever and having its other end pivotally connected to one of said assemblies; means pivotally connecting said lever to the other of said assemblies at a point spaced horizontally from the connection between said link and said` one of said assemblies; and a vertically disposed extensible and contractible hydraulic jack having its upper portion pivotally connected to said main body and its lower end pivotally connected to said lever, said jack being positioned so that its line of thrust passes between said main body assembly and said track frame assembly.

10. The combination as set forth in claim 8 wherein: said vertically disposed link has one end pivotally connected to said track frame assembly; and said second means pivotally connects said lever to said main body assembly.

11. The combination set forth in claim 10 wherein: said attachment includes a mounting bracket rigidly secured to and extending rearwardly from said earth working tool, said bracket being releasably secured to said main body assembly; said second means pivotally connects said lever to said attachment at a point spaced horizontally from said rearwardly disposed transverse axis; and said extensible and contractible jack has its upper portion pivotally connected to said bracket at a location spaced horizontally from said point and axis.

l2. The combination set forth in claim 1l wherein: said earth working tool, said bracket, said lever and said extensible and contractible jack comprise a unitary removable attachment; and said combination includes a means for releasably securing said attachment on said main body assembly.

References Cited in the iile of this patent UNITED` STATES PATENTS 2,073,823 Anthony Mar. 16, 1937 2,078,636 Kuchar Apr. 27, 1937 2,119,373 Wooldridge May 31, 1938 2,312,389 Cordes Mar. 2, 1939 2,312,390 Cordes s Mar. 2, 1939 2,434,693 Graham Ian. 20, 1948 2,495,057 Dillingham Jan. 17, 1950 2,543,989 Rockwell Mar. 6, 1951 

